That's Disgusting: Researcher Studies Gag Reflex

Not many people have had the fortunate pleasure of judging the “Odor-Eaters Rotten Sneakers Contest” held yearly in Montpelier, Vermont. But Rachel Herz, who served as the event’s celebrity judge in March 2008, didn’t just come away with a gag-worthy tale to shock her friends and colleagues. As a fragrance consultant and research psychologist investigating the sense of smell since 1990, Herz was inspired to immerse herself into the study of the emotion of disgust, culminating in her book That’s Disgusting: Unraveling the Mysteries of Repulsion, published by Norton & Company in January. As she writes in the preface: “I have learned that the emotion of disgust is universal, but it is not innate. I have learned that disgust is many things to many people at different times and in different places; and that it is shaped by our situation, culture and personal history.” Miller-McCune spoke with Herz for her thoughts on one area with great potential to elicit disgust: food.

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Miller-McCune: You wrote that the mind has a very powerful influence on our perception and experience of disgust.

Rachel Herz: The emotion of disgust is highly learned. You need an intact, healthy brain in order to turn the mechanism on. But after that, it’s really a function of our experience, culture, and learning. And it’s also highly malleable as a function of the situation we’re in and, specifically, the meaning we ascribe to whatever it is we think we’re perceiving. If you were sitting in a fancy French restaurant and started smelling something and noticed a waiter with a tray, you’d go, “Oh, it must be the cheese course; I’m excited, I’d like to have some taleggio.’” But if you encountered that exact same smell while walking down an alley behind a dive bar, your thoughts would construe the aroma as something totally different. And you’d probably feel totally disgusted.

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M-M: So what happens to us physiologically when we eat something disgusting?

RH: The emotion response of disgust triggers a number of physiological responses, like a drop in blood pressure and an increase in sweating. In extreme cases, you can faint or even vomit. Serotonin gets suffused into the stomach, which is actually an adaptive measure to help initiate vomiting. From a primitive perspective, it’s about protecting us from being contaminated from something on the outside getting into our bodies.

M-M: You write that one of the first and most interesting things you learned about disgust was its impact on facial expressions.

RH: Since one of the core mechanisms of disgust is this idea of shielding the body from the outside, if you look at someone’s face who’s disgusted, you see them squinting their eyes. They’re actually taking in less light to avoiding seeing the disgusting object. In addition, the nose scrunches up and nestles around the cheeks, which closes air off to the nostrils so you can’t catch the smell as well. And our mouths purse as a means to keep things out, or if something got in, it’s a way to get it out. It’s all about protecting the holes on our face, as it were, from contamination.

M-M: Disgust originated in human evolution to protect us from eating poisonous food.

RH: That’s the most simplistic aspect. For example, if you put a drop of quinine on a newborn’s tongue, she’ll make the same grimace as you’d make if I asked you to hold your neighbor’s dirty dentures. What’s interesting is that the response of distaste in reaction to bitter stuff is innate and stereotyped because of the fact that bitter things tend to be poison. Not all bitter things are poison, but it’s a good rule of thumb that if it’s bitter, spit it out. Built onto that very primitive reaction, which animals also have, we find this much higher order level of emotional disgust. So this initial system that protects the body from ingesting poison evolved to protect us from being contaminated by disease.

M-M: So how do you account for the wide variety of disgust levels from person to person and from one age group to another?

RH: One reason is personality. People vary in the degree they’re sensitive to disgust overall. There are also specific things that are more repulsive to one person over another. We each have our own personal levels based on our genetics, temperament, and experience. For example, if I grew up in a household where my parents were very adventurous eaters and I had to take part, then I’d have a completely different attitude toward experimenting with food than if my parents served meatloaf for dinner and peanut butter sandwiches for lunch.

M-M: Culture is another big area where we see a great variation in what's considered disgusting.

RH: Cheese is really interesting, because I think Westerners think of it as either a comfort food or a delicacy. But Asians liken it to cow excrement. Of course, there are comparable things in Asia that repulse Westerners that are considered absolutely delicious — foods like natto, fermented soybeans or 100-year-old fermented eggs. The point is that there’s nothing dangerous at all. In fact, they’re all healthy foods to eat. It’s just how we think of them that makes these foods abhorrent or appealing depending on the culture. Something I think that requires a leap of faith to view as delicious is the drink chicha. This is liquor made out of a collective group’s saliva and mashed up cornmeal that’s allowed to ferment for a month in the ground and become an alcoholic type brew.

M-M: Are there any edible things considered universally disgusting?

RH: I don’t know of any. There’d be no sense in that. The emotion of disgust is basically a luxury of abundance. We have the ability to choose between all kinds of different things to consume. If we were hanging on a thread of survival, we would eat whatever rotten, disgusting, wormy thing was wandering by.

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